Elastic nonwoven fabric and fiber products manufactured therefrom

ABSTRACT

PROBLEM TO BE SOLVED: To provide an elastic nonwoven fabric with a good elasticity, adequate strength under elongation, good antiblocking property and favorable feeling, suitable for fiber products, at low cost, as well as fiber products using the same. 
     SOLUTION: An elastic nonwoven fabric comprising long elastomeric fiber and nonelastomeric fiber in a weight ratio within a range from 50/50 to 95/5, which has an elongation recovery rate of the elastic nonwoven fabric after 50% elongation equal to or higher than 70%, and a resistance to peel two sheets of the nonwoven fabric apart equal to or lower than the strength of the fabric under 50% elongation; as well as fiber products using the same.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to elastic nonwoven fabric and fiberproducts manufactured therefrom. More specifically, it relates toelastic nonwoven fabric having a good elasticity, adequate strengthunder elongation, good antiblocking property, and favorable feeling,which is relatively inexpensive and suitable for fiber products.

2. Description of the Related Art

Elastic nonwoven fabrics have often been used recently to improve bodyfitting of clothes to the body. Such fabrics are particularly suitablefor disposable diapers, clothes, caps, bandages and tapes due to theircomfortable fit, elasticity and stretching property. While thermoplasticelastomers are often used to obtain nonwoven fabrics with suchproperties as mentioned above, most thermoplastic elastomers tend toshow higher adhesiveness with higher elasticity. This renders elasticnonwoven fabrics made from highly elastic thermoplastic elastomersunsuitable, or at most usable only with uncomfortable feeling, forproducts directly applied to the skin under clothes.

Another problem of such nonwoven fabrics is the adhesiveness, by whichthe component fibers stick to each other during production or storage,particularly under high temperatures and the weight of a pile in storagein summer, which results in a higher tension needed for unwinding a rollof such a nonwoven fabric, thus often leading to excessive stretch orbreakdown of the product. Low adhesiveness, or antiblocking nonwovenfabric is needed to solve this problem.

A method for obtaining good antiblocking property is to spin the fiberfor nonwoven fabrics from a mixture of a thermoplastic elastomer with alow adhesiveness polyolefin, as disclosed in Reference 1. However, thenonwoven fabric obtained in this manner shows an insufficientantiblocking property due to scarcity of the polyolefin on the fibersurface, and a low elasticity due to the polyolefin that has only a lowelasticity, and is thus unsuitable for uses mentioned above.

Another invention provides a nonwoven fabric consisting of anelastomeric fiber made from a thermoplastic elastomer blended with anonelastomeric fiber made from a nonelastomeric thermoplastic, asdisclosed in Reference 2. This product is, however, a simple mixture ofthe two fibers without any attempt to obtain high elasticity andantiblocking property simultaneously. In fact, a composition ofelastomeric fiber/nonelastomeric fiber=30/70 on the weight basisdescribed in the examples 1 and 2 of the invention, present in anexcessive proportion of the nonelastomeric fibers, without any treatmentto endow the fabric a high elasticity, cannot provide the excellentperformance desired.

Patent Reference 1

Japanese Patent Application Laid-Open No. 7-81230

Patent Reference 2

Japanese Patent Application Laid-Open No. 2002-242069

Problems to Be Solved by the Invention

The object of the present invention is to provide a nonwoven fabric witha good elasticity, adequate strength under elongation, good antiblockingproperty and favorable feeling, suitable for fiber products, at lowcost, as well as fiber products using the same.

The present inventors have found that the requirements above are met byan elastic nonwoven fabric containing a long elastomeric fiber and anonelastomeric fiber at a ratio ranging from 50/50 to 95/5 on a weightbasis, wherein an elongation recovery rate of the nonwoven fabric after50% elongation is 70% or higher, and a separation resistance of twosheets of the same is equal to or less than the strength at 50%elongation.

SUMMARY OF THE INVENTION

The invention therefore consists in:

-   (1) an elastic nonwoven fabric containing a long elastomeric fiber    and a nonelastomeric fiber at a ratio ranging from 50/50 to 95/5 on    a weight basis, wherein the elongation recovery rate of the nonwoven    fabric after 50% elongation is 70% or higher, and the separation    resistance of two sheets of the same is equal to or less than the    strength at 50% elongation,-   (2) an elastic nonwoven fabric described in (1) above, wherein the    said long elastomeric fiber is manufactured by the melt-blowing    method,-   (3) an elastic nonwoven fabric described in (1) or (2) above,    wherein the said long elastomeric fiber comprises at least one of    the group consists of elastomeric polystyrenes and elastomeric    polyolefins,-   (4) an elastic nonwoven fabric described in any of (1)-(3) above,    wherein the said nonelastomeric fiber has an average diameter (Ad)    of 1 to 20 μm, whereas the said long elastomeric fiber has an    average diameter (Bd) of 5 to 40 μm, and the said two average    diameters are related to each other by Ad≦Bd,-   (5) a laminated elastic nonwoven fabric manufactured by laminating    at least one item chosen from the group consisting of a nonwoven    fabric different from one described in (1) above, film, web,    textile, knit and fiber bundle, to an elastic nonwoven fabric    described in any of (1)-(4) above, and-   (6) a fiber product which employs the elastic nonwoven fabric    described in any of (1)-(4) or the laminated elastic nonwoven fabric    described in (5) above.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention will be described in more detail below.

The elastic nonwoven fabric according to the invention contains a longelastomeric fiber and a nonelastomeric fiber at a ratio ranging from50/50 to 95/5 on a weight basis, wherein the elongation recovery rate ofthe nonwoven fabric after 50% elongation is 70% or higher, and theseparation resistance of two sheets of the same is equal to or less thanthe strength at 50% elongation.

The long elastomeric fiber used in the invention is obtained from aresin composition containing an elastomeric resin as the principalcomponent (the component of the highest content).

An elastomeric resin means a polymer material which shows elasticitysimilar to that of vulcanized rubber (due to soft segments in themolecule) at room temperature (20 to 30° C.), and can be formed intofibers in a conventional machine (due to hard segments in the molecule)at high temperatures. More specifically, it refers to a resin from whicha film is obtained that can be stretched by more than 25% at roomtemperature (20 to 30° C.) and shows an elastic recovery rate ofelongation of 85% or higher at a 25% elongation.

Examples of such elastomeric fibers include polystyrene elastomers,polyolefin elastomers, polyester elastomers, polyamide elastomers, andpolyurethane elastomers. Polystyrene elastomers and polyolefinelastomers are particularly favorable in terms of moldability, chemicalresistance, possibility of regeneration, and environment friendliness(low toxic emission on combustion).

Polystyrene elastomers can be manufactured by copolymerizing an aromaticvinyl compound with other comonomers, such as diene compounds includingbutadiene, isoprene, and chloroprene; olefins including ethylene,propylene, butene and hexene; (meth)acrylic acid and its esters withmethanol, ethanol, butanol, hexanol or other alcohols; and othermonomers susceptible to copolymerization with aromatic vinyl compounds.

Particularly preferable polystyrene elastomers are styrene blockcopolymers containing at least one polymer block (a) chiefly comprisingaromatic vinyl compounds and at least one polymer block (b) chieflycomprising conjugate diene compounds, more than 80% of the double bondsderived from the conjugate dienes being saturated by hydrogen; andrandom copolymers of aromatic vinyl compounds with conjugate dienecompounds. Incidentally, “chiefly comprising” implies here that thecompounds in question account for 50 wt. % or more of a polymer block.

Examples of the aromatic vinyl compounds used in the said styrene blockcopolymers include styrene, α-methylstyrene, vinyltoluene andp-tert-butylstyrene; styrene is particularly preferable. Any of suchcompounds may be used singly or in combination with others. Examples ofthe conjugate diene compounds used in the said styrene block copolymersinclude 1,3-butadiene, isoprene, 1,3-pentadiene,2,3-dimethyl-1,3-butadiene; butadiene and isoprene are particularlypreferable. Any of such compounds may be used singly or in combinationwith others. Eighty percent or more of double bonds in the said styreneblock copolymers, derived from the double bonds in the diene comounds,should preferably be saturated by hydrogen in order to obtain acopolymer with high stability and good spinning property.

Specific examples of such styrene block copolymers includestyrene-ethylenebutylene-styrene block copolymers (SEBSs),styrene-ethylenepropylene-styrene block copolymers (SEPSs) andstyrene-ethylenbutylene-olefin crystalline block copolymers (SEBCs).Commercial products such as Kraton G (Kraton Polymer Japan), Septon(Kuraray), Tuftec (Asahi Chemical) and JSR Dynaron (JSR) belong to thisclass of copolymers.

A preferable example of the said random copolymers of polyethyleneelastomers is a hydrogenated styrene-diene copolymer wherein more than80% of the double bonds derived from the conjugate diene component aresaturated by hydrogen.

Examples of the conjugate diene compounds used as the diene component ofthe said hydrogenated styrene-diene copolymer include 1,3-butadiene,isoprene, 1,3-pentadiene, 2,2-dimethylbutadiene, and 3-ethylbutadiene,among which 1,3-butadiene, isoprene and 1,3-pentadiene are preferable,and 1,3-butadiene is particularly preferable. Examples of the aromaticvinyl compounds used as a component of the said hydrogenatedstyrene-diene copolymer include styrene, α-methylstyrene,p-methylstyrene, p-ethylstyrene and vinylnaphthalene, among whichstyrene, p-methylstyrene and p-ethylstyrene are preferable, and styreneis particularly preferable.

The said hydrogenated styrene-diene copolymer should preferably be acopolymer of at least one conjugate diene compound with aromatic vinylcompounds which account for 3-50 weight % of the polymer, having amolecular weight distribution (Mw/Mn=weight average molecularweight/number average molecular weight) of 10 or lower, the dienecomponent containing 10-90 weight % of vinyl bonds and at least 80% ofolefinic unsaturated bonds in the whole molecule being hydrogenated.

An example of commercial products belonging to this category is JSR'sJSR Dynaron.

Examples of the said polyolefin elastomers include random copolymersconsisting of olefin monomers randomly bonded to each other, and blockcopolymers consisting of hard and soft segments.

Specific examples of the said block copolymers of polyolefin elastomersinclude those chiefly comprising hydrogenated diene copolymers.Preferable hydrogenated diene compounds consist of polymer blocks (c)chiefly comprising conjugate diene compounds rich in 1,4-bonds, andpolymer blocks (d) chiefly comprising conjugate diene compounds rich in1,2- and 3,4-bonds, with the double bonds derived from the dienecopolymers being saturated. Incidentally, “conjugate diene compoundsrich in 1,4-bonds” above implies that the content of 1,4-bonds in thecompound is higher than that of 1,2- or 3,4-bonds, whereas “rich in 1,2-and 3,4-bonds” means that the content of 1,2- and 3,4-bonds is higherthan that of 1,4-bonds, and “chiefly comprising conjugate dienecompounds” implies that the conjugate dienes represent the richestcomponent of the polymer block.

The content of 1,4-bonds in the said polymer blocks (c) composing thesaid hydrogenated diene copolymer is preferably 70 weight % or higher,or more preferably 80 weight % or higher, while the content of the saidpolymer blocks (c) in the said hydrogenated diene copolymer ispreferably 1-99 weight %, or more preferably 5-65 weight %, and mostpreferably 5-50 weight %. Furthermore, the content of 1,2- and 3,4-bondsin the said polymer blocks (d) composing the said hydrogenated dienecopolymer is preferably 25 weight % or higher, or more preferably 30weight % or higher, while the content of the said polymer blocks (d) inthe said hydrogenated diene copolymer is preferably 1-99 weight %, ormore preferably 35-95 weight %, and most preferably 50-95 weight %.

The conjugated diene compounds in the said hydrogenated diene copolymersmay be, for example, 1,3-butadiene, isoprene,2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 2-methyl-1,3-pentadiene,1,3-hexadiene, 4,5-diethyl-1,3-octadiene, 3-butyl-1,3-octadiene, andchloroprene, among which 1,3-butadiene, isoprene and 1,3-pentadiene arepreferable because of commercial availability and because of thepossibility of giving hydrogenated diene copolymers with excellentphysical properties. A preferable example of the hydrogenated dienecopolymers has a numerical average molecular weight of 40,000-700,000wherein 70% or more of the double bonds derived from conjugate dienecomponents are saturated, manufactured by hydrogenating at least one ofthe block copolymers selected from: a (c)-(d) block copolymer, a(c)-(d)-(c) block copolymer, and a block copolymer formed by extensionor branching of such block copolymers over coupler residues, saidpolymer block (c) consisting of polybutadiene containing 25 weight % orless 1,2-bonds and the said polymer block (d) chiefly comprisingconjugate diene compounds containing 50 weight % or more of 1,2- and3,4-bonds derived from the conjugate diene components. Particularlypreferable is a highly elastic fiber known as CEBC manufactured from acrystalline olefin-ethylenebutylene-crystalline olefin block copolymer.JSR's JSR Dynaron is a commercially available example of CEBC. Aphenoxyimine complex catalyst may be used for manufacture of CEBCs.

The present invention utilizes conveniently linear or branchedhydrogenated diene block copolymers wherein the said polymer blocks (d)are copolymers of aromatic vinyl compounds and conjugate diene compoundscontaining 70 weight % or more of the latter, the said conjugate dienecompounds containing 25-70 weight % of vinyl bonds and the blockstructure being represented as (c)-(d-c)n or (c-d)m, where n is aninteger equal to or greater than 1 and m is an integer equal to orgreater than 2. The said aromatic vinyl compounds may be styrene,α-methylstyrene, p-methylstyrene, t-butylstyrene, divinylbenzene,N,N-dimethyl-p-aminoethylstyrene, N,N-diethyl-p-aminoethylstyrene orvinylpyridine, styrene and α-methylstyrene being more preferable.

The random copolymers of polyolefin elastomers mentioned earlier arecopolymers of hydrocarbons with double bonds represented by CnH2n (n isan integer equal to or greater than 2), such as ethylene, propylene orbutene, with at least one monomer different from the same, particularlythose in which the monomer units are arranged randomly.

Random copolymers with a density of 0.850-0.920 g/cm³ are preferable forthe purpose of the invention. Density affects the elasticity of thefiber; a density far higher than 0.920 g/cm³ may result in an extremelylow elasticity of the nonwoven fabric obtained.

The said random copolymers should preferably be copolymers of ethylenewith α-olefins containing 3-10 carbon atoms, or of propylene withα-olefins containing 4-10 carbon atoms, in order to obtain fibers withfavorable feeling and elasticity. More preferable are copolymers ofethylene with α-olefins containing 3-10 carbon atoms, such as propylene,1-butene, 3-methyl-1-butene, 4-methyl-1-butene, 1-pentene, 1-hexene,4-methyl-1-pentene, 1-heptene, 1-octene, 1-nonene, or 1-decene.Particularly preferable α-olefins include 1-butene, 1-pentene, 1-hexeneand 1-octene. Any of these α-olefins may be used singly or incombination with each other, preferable combinations includingethylene-octene and ethylene-butene copolymers. The copolymer ofethylene with α-olefins containing 3-10 carbon atoms, or of propylenewith α-olefins containing 4-10 carbon atoms, used in the inventionshould preferably have a molecular weight distribution (Mw/Mn) of 1.5-4to achieve a favorable spinning property. Such copolymers commerciallyavailable include Engage (DuPont Dow Elastomer Japan) and Tafmer (MitsuiChemical). Metallocene catalysts may be used in the manufacture of thepolyolefin copolymers used in the invention. Furthermore, a diene-basedmonomer may be added to the said α-olefins for crosslinking, yieldingthree-component copolymers such as ethylene-propylene-diene rubber orethylene-butene-diene rubber.

In addition, the said polyolefin elastomers may also be elastomericpolypropylene or propylene-ethylene block copolymers.

Elastomeric polypropylene is a stereo-block copolymer of isotactic orsyndiotactic polypropylene (hard segment) and atactic polypropylene(soft segment). The elastomeric polypropylenes as described in thespecifications U.S. Pat. Nos. 4,335,225, 4,522,982 and 5,188,768, whichcover both homopolymers and copolymers, may thus be used in the presentinvention. The copolymers may contain olefinic units other thanpropylene, such as ethylene, butylene, pentene or hexene, in themolecule. Such copolymers contain substantially stereoregular blockstructure, such as selectively arranged isotactic and atacticpolypropylene blocks, in the backbone.

On the other hand, the said propylene-ethylene block copolymer is a trueblock copolymer, as disclosed in WO 00/23489, in which polypropylene andpoly(ethylene-co-propylene) segments are not simply blended butchemically bonded. As a specific example, a propylene-ethylene blockcopolymer, in which polypropylene segments are covalently bonded topoly(ethylene-co-propylene) segments, can be manufactured by firstsynthesizing a specified quantity of polypropylene segment in aparticular polymerization zone (i) in a short time period, followed bysynthesizing a specified quantity of poly(ethylene-co-propylene) segmentat another polymerization zone (ii), in a polymerization reactor,preferably a tube-type reactor as described in JP09-87343, preferably bya liquid-phase process, in the presence of a titanium-halogen ortitanium-magnesium-halogen solid catalyst and an organometallic olefinpolymerization catalyst, such as triethylaluminum, as well as anoptional electron donor compound added. The propylene-ethylene blockcopolymer thus obtained has a weight average molecular weight (Mw)higher than 100,000, and contains 5-100 weight % of thepoly(ethylene-co-propylene) segment as well as 2-95% of the totalethylene.

The said polyester elastomer may be a polyether ester block copolymerconsisting of a thermoplastic polyester as the hard segment and apolyalkylene glycol as the soft segment. More specifically, it may be athree-component copolymer obtained from at least one dicarboxylic acidselected from: aromatic dicarboxylic acids such as terephthalic acid,isophthalic acid, phthalic acid, naphthalene-2,6-dicarboxylic acid,naphthalene-2,7-dicarboxylic acid, diphenyl-4,4-dicarboxylic acid,diphenoxyethanedicarboxylic acid or 3-sulfoisophthalic acid, alicyclicdicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, aliphaticdicarboxylic acids such as succinic acid, oxalic acid, adipic acid,sebacic acid, dodecanedicarboxylic acid or dimeric acid, andester-forming derivatives thereof; at least one diol selected from:aliphatic diols such as 1,4-butanediol, ethylene glycol, trimethyleneglycol, tetramethylene glycol, pentamethylene glycol, hexamethyleneglycol, neopentyl glycol or decamethylene glycol, alicyclic diols suchas 1,1-cyclohexanedimethanol, 1,4-cyclohexanedimethanol ortricyclodecanedimethanol, and ester-forming derivatives thereof; and atleast one poly(alkylene oxide) glycol selected from: polyethylene glycolor poly(1,2- and 1,3-propylene oxide) glycol with an average molecularweight of about 400-5000, ethylene oxide-propylene oxide copolymer, andethylene oxide-tetrahydrofuran copolymer.

The said polyamide elastomer may be a copolymer of nylon as a hardsegment with a polyester or polyol as a soft segment, such as nylon12-polytetramethylene glycol block copolymer.

A typical example of the said polyurethane elastomer may be obtained bychain extension by a polyamine, chiefly comprising diamines, of aprepolymer having an isocyanate group at either end formed by reacting apolyether and/or polyester with a hydroxy group at either end and anumerical average molecular weight of 1000-6000 with a polyisocyanatechiefly comprising organic diisocyanates.

In the present invention, various stabilizers, UV absorbers, viscocityimprovers, deglossing agents, colorants, rubber or other flexibilityimprovers, or other improvers, may be added to the said elastomericresins as necessary, as far as the addition does not affect theadvantage of the invention.

The elastomeric long fiber in the present invention is obtained byspinning out of the elastomeric resins described above, preferably witha length over 300 mm.

Such long fiber may be manufactured by spraying the thermoplastic resinwith compressed air at high temperatures to open and settle as nonwovenfabric (e.g. the melt blowing method), spinning the resin followed bystretching, opening, collecting and intertwining to obtain nonwovenfabric (e.g. spun-bonding method), or stretching of long thermoplasticresin fiber bundles followed by crimping, opening and expansion (e.g.tow opening method).

Among these methods, the melt blowing and spun-bonding processes arepreferable because of high productivity, low production costs, ease ofproduction and the feeling of products. Melt-blown nonwoven fabricpresents comfortable feeling because of low average diameter of thecomponent fibers, while spunbonded nonwovens have high strength becausethe component fibers are stretched continuous long fibers. Thesenonwoven fabrics may be surface treated as necessary, e.g. withsurfactants.

The nonelastomeric fiber in the invention is obtained from resincompositions chiefly comprising nonelastomeric resins. Although itsfunction is only to provide the elastic nonwoven fabric withantiblocking property and favorable feeling, it is preferable for a filmobtained from the said resin, with 25% elongation, to have an elasticrecovery rate of elongation less than 85%, or more favorably less than80%.

Such a nonelastomeric resin may be polyesters, polyamides orpolyolefins. Polyolefins are preferable because of low costs and ease ofprocessing in addition to favorable feeling and slip given to thenonwoven fabric obtained. Polypropylene and polyethylene areparticularly preferred from this respect.

In the present invention, various stabilizers, UV absorbers, viscosityimprovers, deglossing agents, colorants, rubber or other flexibilityimprovers, or other improvers, may be added to the nonelastomeric resinsas necessary, as far as the addition does not affect the advantage ofthe invention.

The nonelastomeric fiber in the invention is manufactured by spinningthe said resin composition chiefly comprising nonelastomeric resins intofiber.

No particular restriction is imposed on the method to manufacture suchnonelastomeric fibers; examples include production of short fibers suchas staple fibers or chopped fibers, and production of long fibers suchas melt blowing, spun-bonding and tow opening. Melt blowing andspun-bonding are preferred for the feeling and strength, respectively,of the product.

The elastic nonwoven fabric according to the invention contains a longelastomeric fiber and a nonelastomeric fiber at a ratio ranging from50/50 to 95/5 on a weight basis; the ratio ranges preferably from 50/50to 90/10, or more desirably 60/40 to 90/10. A relative weight of thelong elastomeric fiber under said range leads to a fabric withinsufficient elasticity, while one over said range to a sticky fabricwith poor antiblocking property.

According to the invention, the nonelastomeric fiber is mixed with theelastomeric fiber to provide the elastic nonwoven fabric with anantiblocking property and favorable feeling. The mixing may be performedin any of the known methods. For example, a melt blowing process ofelastomeric long fiber production may have a step in which short, longor chopped nonelastomeric fiber is fed while long elastomeric fiber issprayed onto a collecting conveyor net. An alternative may be sprayingmelt-blown long elastomeric fiber while forming a web of short or longfiber.

When using melt-blown long fiber as the nonelastomeric fiber composingthe elastic nonwoven fabric of the invention, a spinneret as describedin U.S. Pat. No. 3,981,650 may be used which has spinning holes fordifferent resins alternately arranged in a row. The elastomeric andnonelastomeric long fibers are more uniformly mixed in the web producedin this manner. Alternatively, separate spinnerets may be used forelastomeric and nonelastomeric resin, respectively, to obtain longelastomeric fiber and long nonelastomeric fiber webs which aresubsequently laminated and, as necessary, further processed to improvefiber mixing by e.g. needle punching. A more uniformly mixed web may beobtained using the spinneret disclosed in U.S. Pat. No. 3,981,650.

The content of the elastomeric and nonelastomeric fibers in the elasticnonwoven fabric may be modified by changing the number of holesallocated to the elastomeric and nonelastomeric resins, or bycontrolling the extrusion rate of each resin. A mixture of fibers withdifferent fineness may be manufactured by spinning each resin atdifferent extrusion rates through the spinning holes allocated, or byspinning through spinnerets with different opening diameters.

When using spunbonded long fiber as the nonelastomeric fiber composingthe elastic nonwoven fabric of the invention, a spinneret as shown inFIG. 1 may be used, which has spinning holes for different resinsarranged in a staggered manner. The elastomeric and nonelastomeric longfibers are more uniformly mixed in the web produced in this manner.Alternatively, separate spinnerets may be used for elastomeric andnonelastomeric resin, respectively, to obtain long elastomeric fiber andlong nonelastomeric fiber webs which are subsequently laminated and, asnecessary, further processed to improve fiber mixing by e.g. needlepunching.

The content of the elastomeric and nonelastomeric fibers in the elasticnonwoven fabric may be modified by changing the number of holesallocated to the elastomeric and nonelastomeric resins, or bycontrolling the extrusion rate of each resin. A mixture of fibers withdifferent fineness may be manufactured by spinning each resin atdifferent extrusion rates through the spinning holes allocated, or byspinning through spinnerets with different opening diameters.

The elastic nonwoven fabric according to the invention has at least twocomponents: an elastomeric resin and a nonelastomeric resin. It may be athree- or four-component composition containing different elastomericand/or nonelastomeric long fiber, but the two-component system ispreferred with respect to production costs or productivity.

The cross section of the long or short fiber composing the nonwovenfabric of the invention may be circular, other forms, or even hollow, asfar as the spinning properties remain unaffected. The average diameterof the long or short fiber is not restricted in particular. A lowaverage diameter (Bd) of the long elastomeric fiber gives the productfavorable feeling but results in barely satisfactory elasticity andstrength. On the other hand, a high Bd leads to satisfactory elasticityand strength accompanied by poor feeling. Practically, therefore, theaverage diameter (Bd) of the long elastomeric fiber should preferablyrange from 5 to 40 μm, or, to obtain favorable feeling, from 5 to 30 μm.

The principal role of the nonelastomeric fiber in the invention is toimprove the antiblocking property. A lower average diameter (Ad) of thenonelastomeric fiber means a higher relative surface area of it in thenonwoven fabric, which results in more effective antiblocking due toincreased coverage of the long elastomeric fiber. Although a low contentof the nonelastomeric fiber in the nonwoven fabric will generally resultin a poor antiblocking property, this can be compensated for by reducingthe average diameter (Ad) of the nonelastomeric fiber. The preferredaverage diameter (Ad) of the nonelastomeric fiber is, therefore, 1-20μm, taking productivity into account, or rather 1-10 μm, consideringalso feeling of the product. In addition, it is desirable that thediameters of the two fibers be in a relation Ad≦Bd and Bd/Ad≧2, or moredesirably Bd/Ad≧5.

The relation Ad≦Bd assures satisfactory elasticity, strength andantiblocking property of the nonwoven fabric produced. Even in a hot andhumid season that tends to cause blocking of long elastomeric fiber, therelation controls blocking because the contact area between the longfibers is maintained at a relatively low level. Laminating at least oneside of the elastic nonwoven fabric with a thin web of finenonelastomeric fiber, as far as it does not impair the elasticity of theformer, is an effective way to prevent blocking.

The elastic nonwoven fabric of the invention should show an elongationrecovery rate after 50% elongation is 70% or higher, preferably 80% orhigher, or more desirably 90% or higher. A fabric with an elongationrecovery rate after 50% elongation of far lower than 70% results inproducts with poor elasticity. For example, a disposable shorts-typediaper involving such a fabric may not fit well because it does notrecover completely from the stretch when wearing.

A feature of the invention is mixing the elastic and adhesive longelastomeric fiber with the low-sticking nonelastomeric fiber. Increasingthe weight ratio of the long elastomeric fiber(elastomeric/nonelastomeric) leads to increase in elasticity (elongationrecovery rate after 50% elongation); conversely, increasing the weightratio of the nonelastomeric fiber results in good antiblocking property.

Good antiblocking property is reflected in a low resistance in peelingapart two sheets of elastic nonwoven fabric (referred to as “peelingstrength” hereinafter). The elastic nonwoven fabric is usually wound uponto a roller for storage, and unwound as necessary for furtherprocessing. A low peeling strength of the fabric means that the fabriccan be unwound by a tension low enough not to cause plastic deformationof the fabric, thus assuring ease of operation and high product quality.

Conversely, a fabric with a high peeling strength requires a hightension for separating the fabric layers in contact when unwinding,leading to breakage, or excessive elongation that prevents furtherprocessing of the fabric.

The elastic nonwoven fabric according to the invention should have apeeling strength less than the strength at 50% elongation to maintainthe ease of handling and product quality. Specifically, thisspecification overcomes the problem for elastic nonwoven fabric rollsprepared in summer which otherwise tend to present difficulty inunwinding because of adhesion between fiber yarns due to hightemperatures and loads.

Although the elastic nonwoven fabric according to the invention may haveany basic weight, a common range of basic weight is 5-300 g/m²; apreferable range of basic weight is 10-200 g/m²; a range of 20-150 g/m²is particularly desirable. The nonwoven fabric may be heat-treated, asnecessary, between the softening point of the elastomeric resin used inthe fabric and that of the nonelastomeric resin, in any of the knownmethods including thermocompression under heated embossing rollers, airthrough bonding by hot air, and IR lamp irradiation. Moreover, otherprocessing, such as sonic bonding, water jetting, needle punching,and/or resin bonding, may be performed on the fabric.

It is also possible to stretch the nonwoven fabric itself manufacturedaccording to the invention. On stretching the fabric, the nonelastomericfiber is elongated while the long elastic fiber restores its originallength elastically, thus avoiding any interference of the nonelastomericfiber to the elasticity of the fabric. This is a particularly desirableembodiment of the invention because it gives a bulky nonwoven fabricwith favorable feeling.

A specific example of such a processing is stretching the nonwovenfabric at 20-30° C. in the machine direction (MD) or cross-machinedirection (CD) to 1.2 times or higher (insofar as not to causebreakage), preferably to 1.5-3.5 times, or more desirably 2.0-3.2 timesthe original length, followed by relaxation and winding into a roll. Theproduct has particularly good elasticity in the stretched direction.

The direction of stretching in the said stretching processing is notrestricted, but determines the direction of preferred elasticity.

The present invention covers also laminated elastic nonwoven fabricsobtained by laminating to the fabric at least one of the groupcomprising nonwoven fabric other than the product itself, film, web,textile, knit and fiber bundle. The laminating material shouldpreferably provide the fabricated laminate with an elongation of 20% orhigher in order not to deter elongation of the elastic nonwoven fabric.Examples include nonwoven fabric, net and film manufactured bymelt-blowing from thermoplastic elastomers such as polystyreneelastomers, polyolefin elastomers, polyester elastomers or polyurethaneelastomers. Knit or textile made of fibers derived from thermoplasticelastomeric resins, such as polystyrene elastomers, polyolefinelastomers, polyester elastomers or polyurethane elastomers; web,nonwoven fabric, textile or knit made of nonelastomeric materialsrendered elastic structurally by crimping may also be used. Furthermore,curded or air-laid web may be laminated by water jet, point bonding orthrough air bonding. These examples, however, do not limit the scope ofthe invention.

The elastic nonwoven fabric according to the invention may be used inthe elastic members of sanitary products such as diapers, disposablediapers, sanitary napkins and diaper covers, elastic tapes, adhesiveplasters, and elastic members of clothes. It may also be used ininterfacing for clothes, electric and heat insulators for clothes,protective wear, hats, masks, gloves, supporters, stretch bandages,poultice substrates, plaster substrates, non-slip substrates, vibrationabsorbers, fingerstalls, filters (air filters for clean rooms, bloodfilters, oily water separation filters, electret filters), separators,heat insulators, coffee bags, food packaging, vehicle members (ceilingfacings, soundproof materials, substrates, cushions, loudspeakerscreens, air cleaners, insulator facings, backings, bonded nonwovenfabrics for seats, door trimmings), cleaning materials including thosefor copying machines, carpet facings, agricultural sheets, wood drainingmaterials, shoe members e.g. sports shoes facings, bag members,industrial sealing materials, wiping materials and bed sheets. Theseexamples do not limit the scope of the invention.

EXAMPLES

The invention is further described below using examples and comparativeexamples. They do not limit the scope of the invention. Measurementresults quoted in the examples were obtained by the methods describedbelow.

(i) Elongation recovery rate after 50% elongation

A test piece, 25 mm wide and 200 mm long (in the machine direction), ofthe nonwoven fabric was mounted to a testing machine (Shimadzu AutographAG-G) at a chuck distance of 100 mm. The test piece was stretched up to50% at a rate of 300 mm/min, and the machine was reversed at the samerate until the load on the test piece vanished. The piece was againstretched immediately up to 50% at the same rate, and the length L (mm)was measured when the load appeared. The elongation recovery rate after50% elongation was calculated by the formula:Elongation recovery rate after 50% elongation(%)={(100(*1)−L)/100(*1)}×100(*1): Initial length of the test piece (mm)(ii) Strength at 50% elongation

A test piece, 25 mm wide and 200 mm long (in the machine direction), ofthe nonwoven fabric was mounted to a testing machine (Shimadzu AutographAG-G) at a chuck distance of 100 mm. The test piece was stretched at arate of 300 mm/min, and the load at 50% elongation (N/25 mm) wasmeasured.

(iii) Feeling

A sheet of the nonwoven fabric 100×100 mm in size was given to a panelconsisting of 10 members for evaluation of the feeling by touch. Eachpanelist answered with a point on a 10-point scale. The evaluation wasbased on the total of the panelists' answers, i.e. on a 100-point scale.The feeling of the specimen was evaluated as good when it acquired 60points or more, or preferably 70 points or more.

(iv) Peeling strength

Two sheets of the nonwoven fabric 100×100 mm in size were superimposed,upon which an aluminum plate 100×100 mm in size was laid with weightssuch that the total load on the fabric was 5 kg. The assembly was placedin an oven and maintained at 50° C. for 24 hours. The test piece wasthen cut to a width of 25 mm in a room environment of 25° C. and 65% RH.One end of the piece 50 mm in length was peeled apart by hand, and eachof the separated ends was fixed onto the chucks of the testing machine(Shimadzu Autograph AG-G) at a distance of 50 mm. The specimen wasstretched at a rate of 100 mm/min until the two sheets were completelyseparated. An average of five measurements was taken as the peelingstrength (N/25 mm) result. A low peeling strength indicates a favorableantiblocking property.

(v) Average fiber diameter

Five sheets 10×10 mm in size were cut out of the elastic nonwoven fabricat arbitrary locations for observation by a scanning electron microscope(JEOLCO).

Diameters were measured for twenty fibers in each sheet, and the totalof 100 measurements was averaged to obtain the fiber diameter (D). Thesheets were then treated with an appropriate solvent selected from thelist below in a Soxhlet extractor to remove the elastomeric fiber, andsubsequently underwent similar measurements to determine the averagefiber diameter of the nonelastomeric fiber (Ad).Meanwhile, the weight ratio of the long elastomeric fiber/nonelastomericfiber was separately measured, and the densities of the component resinswere determined after JIS L 1015 (density gradient tube method). Thesedata were used to convert the weight ratio of the component fibers tothe volumetric ratio for calculation of the average fiber diameter ofthe long elastomeric fiber (Bd) as follows.If the density of the long elastomeric fiber is Bρ, that of thenonelastomeric fiber is Aρ, and their weight ratio is Bw/Aw, thevolumetric fraction of the long elastomeric fiber isBv=(Bw/Bρ)/{(Bw/Bρ)+(Aw/Aρ)}and that of the nonelastomeric fiber isAv=(Aw/Aρ)/{(Bw/Bρ)+(Aw/Aρ)}.Therefore the diameter of the long elastomeric fiber isti Bd=(D−Ad×Av)/Bv(Extraction Solvents)For polyurethane elastomers: Conc. hydrochloric acidFor polystyrene elastomers: TolueneFor polyolefin elastomers: TolueneFor polyamide elastomers: AnilineFor polyester elastomers: Conc. sulfuric acid

Materials used in the invention are listed below with correspondingsymbols.

Elastomeric Resins

-   B-1: Syrene-ethylenebutylene-styrene block copolymer, Kraton G 1657    (Kraton Polymer Japan)-   B-2: Syrene-ethylenebutylene-styrene block copolymer, Dynaron 8600P    (JSR)-   B-3: Crystalline olefin-ethylenebutylene-crystalline olefin block    copolymer, Dynaron 6200P (JSR)-   B-4: Hydrogenated styrene-diene copolymer, Dynaron 2324P (JSR)-   B-5: Ethylene-octene copolymer, Engage 8401 (DuPont Dow Elastomer    Japan)-   B-6: B-1 blended with B-5 at a ratio 1:1 on weight basis.-   B-7: Thermoplastic urethane polymer, Pandex T-1180 (DIC Bayer    Polymer)-   B-8: Polyester elastomer, Grilux E-200LV (Dainippon Ink Chemical)-   B-9: Polyamide elastomer, Pebax 2533 (Atofina Japan)-   B-10: B-2 blended with B-5 at a ratio 95:5 on weight basis.    Nonelastomeric Resins-   A-1: Polypropylene, Chisso Polypro CS3300 (Chisso)-   A-2: Propylene-ethylene-butene copolymer (4 wt % ethylene, 2.65 wt %    butene), Chisso Polypro CS 3650 (Chisso)-   A-3: Polyethylene, Chisso Polyethy S6900 (Chisso)-   A-4: Polyethylene terephthalate, K101 (Kanebo)

Example 1

A melt-blown nonwoven fabric was manufactured from the elastomeric resinB-1 and nonelastomeric resin A-1 in an apparatus comprising twoextruders equipped with a screw 30 mm in diameter, heating elements anda gear pump, spinnerets for combined yarns (501 holes 0.3 mm indiameter, alternately for different yarns arranged in a row, 500 mm ineffective width), an air compressor, an air heater, a collectingconveyor with a polyester net, and a take-up. The elastomeric andnonelastomeric resins were charged in the respective extruders, andmelted by heating to 230° C. and 270° C., respectively. The gear pumpswere set so that the weight ratio of the elastomeric/nonelastomericresin was 95/5. The molten B-1 resin was discharged through thespinneret at a rate of 0.242 g per minute per hole, and the molten A-1at 0.013 g per minute per hole. The threads formed were blown onto theconveyor, located at a distance of 25 cm from the spinneret and runningat a rate of 2 m/min, by means of compressed air at 98 kPa (gauge)heated to 400° C. The air was removed by a suction unit behind theconveyor. The load on the conveyor was rolled up as elastic nonwovenfabric with a basic weight of 60 g/m². Properties of the fabric aresummarized in Table 1. This nonwoven fabric showed a good elasticity andantiblocking property, an adequate strength at 50% elongation, andfavorable feeling.

Example 2

An elastic nonwoven fabric was manufactured as in Example 1, except thatthe weight ratio of the elastic/nonelastic resin was 90/10 and thespinning rate was 0.230 g per minute per hole for B-1 and 0.026 g perminute per hole for A-1. Properties of the fabric obtained aresummarized in Table 1. This nonwoven fabric showed a good elasticity andantiblocking property, an adequate strength under elongation, andfavorable feeling.

Example 3

An elastic nonwoven fabric was manufactured as in Example 1, except thatthe weight ratio of the elastic/nonelastic resin was 80/20 and thespinning rate was 0.204 g per minute per hole for B-1 and 0.051 g perminute per hole for A-1. Properties of the melt-blown elastic nonwovenfabric obtained are summarized in Table 1. This nonwoven fabric showed agood elasticity and antiblocking property, an adequate strength underelongation, and favorable feeling.

A laminated elastic nonwoven fabric was manufactured by laminating amelt-blown nonwoven fabric made of the resin A-1, with a fiber diameterof 2 μm and a basic weight of 2 g/m², onto the fabric obtained inExample 3 using a hot embossed roller. The laminated fabric 2000 m inlength was rolled and stored in a room at a temperature of 50° C. andhumidity of 80%, simulating a warehouse environment in summer, for sevendays. Subsequent measurement showed a peeling strength of 0.5 N/25 mm,indicating good antiblocking property.

The nonwoven fabric of Example 3 was substituted for the elastic netused in both sides of a commercial shorts-type disposable diaper(Procter & Gamble Far East, “Pampers Suku-Suku Pants L”). The modifieddiapers were provided for trial by five infants. No subject showed anymark of, or rash caused by, excessively tight fitting, or slippage orexcrement escape due to poor fitting.

Another laminated nonwoven fabric was manufactured by placing a stretchynonwoven fabric consisting of three-dimensionally crimpled polyolefinstaple fiber, 100 g/m² in basic weight, upon the fabric obtained inExample 3 and intertwining by water jet. Supporters were manufacturedfrom this fabric and provided for trial by five monitors. Afterapplication around the knee for 24 hours, no subject showed any mark of,or rash caused by, excessively tight fitting, or slippage due to poorfitting.

Adhesive plaster was manufactured by coating one side of the fabric ofExample 3 with an adhesive, and applying cloth coated with a hemostaticagent onto it. The plaster was provided for trial by ten monitors. Afterapplication around the index finger for 24 hours, no subject showed anymark of, or rash caused by, excessively tight fitting, or slippage dueto poor fitting.

Surgical tape was manufactured by coating one side of the fabric ofExample 3 with an adhesive, and was provided for trial by ten monitors.After application around the elbow for 24 hours, no subject showed anymark of, or rash caused by, excessively tight fitting, or slippage dueto poor fitting.

A poultice was prepared by applying an analgesic onto the fabric ofExample 3 and was provided for trial by ten monitors. After applicationaround the knee for 24 hours, no subject showed any mark of, or rashcaused by, excessively tight fitting, or slippage due to poor fitting.

Example 4

The elastic nonwoven fabric obtained in Example 3 was stretched 2.2times in the machine direction at 23° C., relaxed and wound up into aroll. Properties of the stretched fabric are summarized in Table 1. Thisfabric showed a good elasticity and antiblocking property, an adequatestrength under elongation, and favorable feeling.

The nonwoven fabric of Example 4 was substituted for the elastic netused in both sides of a commercial shorts-type disposable diaper(Procter & Gamble Far East, “Pampers Suku-Suku Pants L”). The modifieddiapers were provided for trial by five infants. No subject showed anymark of, or rash caused by, excessively tight fitting, or slippage orexcrement escape due to poor fitting.

Adhesive plaster was manufactured by coating one side of the fabric ofExample 4 with an adhesive, and applying cloth coated with a hemostaticagent onto it. The plaster was provided for trial by ten monitors. Afterapplication around the index finger for 24 hours, no subject showed anymark of, or rash caused by, excessively tight fitting, or slippage dueto poor fitting.

Surgical tape was manufactured by coating one side of the fabric ofExample 4 with an adhesive, and was provided for trial by ten monitors.After application around the elbow for 24 hours, no subject showed anymark of, or rash caused by, excessively tight fitting, or slippage bypoor fitting.

Example 5

An elastic nonwoven fabric was manufactured as in Example 1, except thatthe weight ratio of the elastic/nonelastic resin was 70/30 and thespinning rate was 0.179 g per minute per hole for B-1 and 0.077 g perminute per hole for A-1. Properties of the fabric obtained aresummarized in Table 1. This nonwoven fabric showed a good elasticity andantiblocking property, an adequate strength under elongation, andfavorable feeling.

Example 6

An elastic nonwoven fabric was manufactured as in Example 1, except thatthe weight ratio of the elastic/nonelastic resin was 60/40 and thespinning rate was 0.153 g per minute per hole for B-1 and 0.102 g perminute per hole for A-1. Properties of the fabric obtained aresummarized in Table 1. This nonwoven fabric showed a good elasticity andantiblocking property, an adequate strength under elongation, andfavorable feeling.

Example 7

An elastic nonwoven fabric was manufactured as in Example 1, except thatthe weight ratio of the elastic/nonelastic resin was 50/50 and thespinning rate was 0.128 g per minute per hole for B-1 and 0.128 g perminute per hole for A-1. Properties of the fabric obtained aresummarized in Table 1. This nonwoven fabric showed a good elasticity andantiblocking property, an adequate strength under elongation, andfavorable feeling.

Example 8

An elastic nonwoven fabric was manufactured under processing conditionsand using manufacturing apparatus similar to those in Example 1, exceptthat the weight ratio of the elastic/nonelastic resin was 85/15 and thespinning rate was 0.217 g per minute per hole for B-1 and 0.038 g perminute per hole for A-1. Properties of the fabric obtained aresummarized in Table 1. This nonwoven fabric showed a good elasticity andantiblocking property, an adequate strength under elongation, andfavorable feeling.

Example 9

An elastic nonwoven fabric was manufactured as in Example 1, except thatthe weight ratio of the elastic/nonelastic resin was 25/75 and thespinning rate was 0.064 g per minute per hole for B-1 and 0.191 g perminute per hole for A-1. Properties of the fabric obtained aresummarized in Table 1. This nonwoven fabric showed a good elasticity andantiblocking property, an adequate strength under elongation, andfavorable feeling.

Example 10

An elastic nonwoven fabric was manufactured from the elastomeric resinB-2 and nonelastomeric resin A-1, melted by heating to 270° C. and 200°C., respectively. The gear pumps were set so that the weight ratio ofthe elastomeric/nonelastomeric resin was 80/20. The molten B-2 resin wasdischarged through the spinneret at a rate of 0.204 g per minute perhole, and the molten A-1 at 0.051 g per minute per hole. The threadsformed were blown onto the conveyor, located at a distance of 25 cm fromthe spinneret and running at a rate of 2 m/min, by means of compressedair at 98 kPa (gauge) heated to 400° C. Properties of the fabric aresummarized in Table 1. This nonwoven fabric showed a good elasticity andantiblocking property, an adequate strength under elongation, andfavorable feeling.

Example 11

The elastic nonwoven fabric obtained in Example 10 was stretched 2.2times in the machine direction at 23° C., relaxed and wound up into aroll. Properties of the stretched fabric are summarized in Table 2. Thisfabric showed a good elasticity and antiblocking property, an adequatestrength under elongation, and particularly favorable feeling.

Example 12

An elastic nonwoven fabric was manufactured from the elastomeric resinB-1 and nonelastomeric resin A-2 in the same process as in Example 3.Properties of the fabric are summarized in Table 2. This fabric showed agood elasticity and antiblocking property, an adequate strength underelongation, and favorable feeling.

Example 13

The elastic nonwoven fabric obtained in Example 12 was stretched 2.2times in the machine direction at 23° C., relaxed and wound up into aroll. Properties of the stretched fabric are summarized in Table 2. Thisfabric showed a good elasticity and antiblocking property, an adequatestrength under elongation, and particularly favorable feeling.

Example 14

An elastic nonwoven fabric was manufactured from the elastomeric resinB-1 and nonelastomeric resin A-3 in the same process as in Example 3.Properties of the fabric are summarized in Table 2. This fabric showed agood elasticity and antiblocking property, an adequate strength underelongation, and favorable feeling.

Example 15

An elastic nonwoven fabric was manufactured from the elastomeric resinB-1 and nonelastomeric resin A-4 in the same process as in Example 3.Properties of the fabric are summarized in Table 2. This fabric showed agood elasticity and antiblocking property, an adequate strength underelongation, and favorable feeling.

Example 16

An elastic nonwoven fabric was manufactured from the elastomeric resinB-3 and nonelastomeric resin A-1 in the same process as in Example 3.Properties of the fabric are summarized in Table 2. This fabric showed agood elasticity and antiblocking property, an adequate strength underelongation, and favorable feeling.

Example 17

An elastic nonwoven fabric was manufactured from the elastomeric resinB-4 and nonelastomeric resin A-1 in the same process as in Example 3.Properties of the fabric are summarized in Table 2. This fabric showed agood elasticity and antiblocking property, an adequate strength underelongation, and favorable feeling.

Example 18

An elastic nonwoven fabric was manufactured from the elastomeric resinB-5 and nonelastomeric resin A-1 in the same process as in Example 3.Properties of the fabric are summarized in Table 2. This fabric showed agood elasticity and antiblocking property, an adequate strength underelongation, and favorable feeling.

Example 19

An elastic nonwoven fabric was manufactured from the elastomeric resinB-6 and nonelastomeric resin A-1 in the same process as in Example 3.Properties of the fabric are summarized in Table 2. This fabric showed agood elasticity and antiblocking property, an adequate strength underelongation, and favorable feeling.

Example 20

An elastic nonwoven fabric was manufactured from the elastomeric resinB-7 and nonelastomeric resin A-1 in the same process as in Example 3.Properties of the fabric are summarized in Table 2. This fabric showed agood elasticity and antiblocking property, an adequate strength underelongation, and favorable feeling.

Example 21

An elastic nonwoven fabric was manufactured from the elastomeric resinB-8 and nonelastomeric resin A-1 in the same process as in Example 3.Properties of the fabric are summarized in Table 3. This fabric showed agood elasticity and antiblocking property, an adequate strength underelongation, and favorable feeling.

Example 22

An elastic nonwoven fabric was manufactured from the elastomeric resinB-9 and nonelastomeric resin A-1 in the same process as in Example 3.Properties of the fabric are summarized in Table 3. This fabric showed agood elasticity and antiblocking property, an adequate strength underelongation, and favorable feeling.

Example 23

Short fiber 2 dtex in fineness and 5 mm in length was prepared from thenonelastomeric resin A-1 using an extruder equipped with a screw 30 mmin diameter, heating elements and a gear pump, a spinning apparatuscomprising a spinneret (500 holes 0.6 mm in diameter), a godet rollerand a take-up, and a hot-roller stretcher. A melt-blown nonwoven fabricwas manufactured from the elastomeric resin B-1 in an apparatuscomprising an extruder equipped with a screw 30 mm in diameter, heatingelements and a gear pump, a spinneret (501 holes 0.3 mm in diameter, 500mm in effective width), an air compressor, an air heater, a collectingconveyor with a polyester net, and a take-up. The elastomeric resin wascharged in the extruder, melted by heating to 230° C., and dischargedthrough the spinneret. The threads formed were blown onto the conveyor,located at a distance of 25 cm from the spinneret and running at a rateof 2 m/min, by means of compressed air at 98 kPa (gauge) heated to 400°C. The air was removed by a suction unit behind the conveyor.

The nonelastomeric short fiber prepared above was supplied into themelt-blowing air so that the weight ratio of long elastomericfiber/short nonelastic fiber=80/20 and that the fibers are mixeduniformly. The load on the conveyor was point-bonded at 120° C. using anembossed roller with a pressurized area ratio of 24%, and finally rolledup as elastic nonwoven fabric with a basic weight of 60 g/m².

Properties of the fabric obtained are summarized in Table 3. Thisnonwoven fabric showed a good elasticity and antiblocking property, anadequate strength under elongation, and favorable feeling.

Example 24

An elastic nonwoven fabric was manufactured from the elastomeric resinB-1 and nonelastomeric resin A-1 in the same process as in Example 3,except that the nonelastomeric resin was melted by heating to 240° C.Properties of the fabric are summarized in Table 3. This fabric showed agood elasticity and antiblocking property, an adequate strength underelongation, and favorable feeling.

Example 25

An elastic nonwoven fabric was manufactured from the elastomeric resinB-1 and nonelastomeric resin A-1 in the same process as in Example 3,except that the nonelastomeric resin was melted by heating to 210° C.and the elastomeric resin to 240° C. Properties of the fabric aresummarized in Table 3. This fabric showed a good elasticity andantiblocking property, an adequate strength under elongation, andfavorable feeling.

Example 26

A spunbonded nonwoven fabric was manufactured from the elastomeric resinB-1 and nonelastomeric resin A-1 in an apparatus comprising twoextruders equipped with a screw 40 mm in diameter, heating elements anda gear pump, spinnerets for combined yarns shown in FIG. 1 (120 holes0.4 mm in diameter), an air sucker, an electrostatic opening machine, acollecting conveyor with a polyester net, a point-bonding machine, and atake-up. The elastomeric and nonelastomeric resins were charged in therespective extruders, and melted by heating to 230° C. and 270° C.,respectively. The gear pumps were set so that the weight ratio of theelastomeric/nonelastomeric resin was 80/20. The molten B-1 resin wasdischarged through the spinneret at a rate of 0.46 g per minute perhole, and the molten A-1 at 0.11 g per minute per hole. The threadsformed were introduced in the air sucker (196 kPa), and immediatelyopened by the electrostatic opening machine, before being finallycollected by the conveyor. The web on the conveyor was then introducedinto the point-bonding machine (a roller temperature of 90° C., contactarea ratio of 15%), and the finished product was rolled up as elasticnonwoven fabric with a basic weight of 60 g/m². Properties of the fabricare summarized in Table 3. This nonwoven fabric showed a good elasticityand antiblocking property, an adequate strength under elongation, andfavorable feeling.

Example 27

An elastic long-fibered nonwoven fabric was manufactured from theelastomeric resin B-5 and nonelastomeric resin A-1 in the same processas in Example 26, except that the nonelastomeric resin was melted byheating to 240° C. Properties of the fabric are summarized in Table 3.This fabric showed a good elasticity and antiblocking property, anadequate strength under elongation, and favorable feeling.

Example 28

The elastic nonwoven fabric obtained in Example 26 was stretched 2.2times in the machine direction at 23° C., relaxed and wound up into aroll. Properties of the stretched fabric are summarized in Table 3. Thisfabric showed a good elasticity and antiblocking property, an adequatestrength under elongation, and particularly favorable feeling.

Example 29

The elastic nonwoven fabric obtained in Example 27 was stretched 2.2times in the machine direction at 23° C., relaxed and wound up into aroll. Properties of the stretched fabric are summarized in Table 3. Thisfabric showed a good elasticity and antiblocking property, an adequatestrength under elongation, and particularly favorable feeling.

Comparative Example 1

An elastic nonwoven fabric was manufactured from the elastomeric resinB-1 and nonelastomeric resin A-1 as in Example 1, except that the weightratio of the elastic/nonelastic resin was 99/1, the spinning rate was0.252 g per minute per hole for B-1 and 0.003 g per minute per hole forA-1, and the conveyor speed was 2 m/min. Properties of the fabricobtained are summarized in Table 4. This fabric showed unsatisfactoryperformance with the peeling strength higher than the strength underelongation.

Comparative Example 2

An elastic nonwoven fabric was manufactured from the elastomeric resinB-1 and nonelastomeric resin A-1 as in Example 1, except that the tworesins were blended at a ratio of B-1/A-1=90/10 on the weight basisbefore being fed to the extruder, and that the spinning rate for themixture was 0.26 g per minute per hole. Properties of the fabricobtained are summarized in Table 4. This fabric showed unsatisfactoryperformance with the peeling strength higher than the strength underelongation.

Comparative Example 3

An elastic nonwoven fabric was manufactured from the elastomeric resinB-1 only under processing conditions and in an apparatus similar tothose in Example 2. Properties of the fabric obtained are summarized inTable 4. This fabric showed unsatisfactory performance with the peelingstrength higher than the strength under elongation.

Comparative Example 4

An elastic nonwoven fabric was manufactured from the elastomeric resinB-1 and nonelastomeric resin A-1 as in Example 1, except that the weightratio of the elastic/nonelastic resin was 40/60, and the spinning ratewas 0.102 g per minute per hole for B-1 and 0.153 g per minute per holefor A-1. Properties of the fabric obtained are summarized in Table 4.This fabric showed unsatisfactory performance with too low an elasticrecovery rate of 50% elongation.

Comparative Example 5

An elastic nonwoven fabric was manufactured from the elastomeric resinB-1 and nonelastomeric resin A-1 as in Example 1, except that the tworesins were blended at a ratio of B-1/A-1=50/50 on the weight basisbefore being fed to the extruder, and that the spinning rate for themixture was 0.26 g per minute per hole. Properties of the fabricobtained are summarized in Table 4. This fabric consisting of an equalamount of the elastic and nonelastic resins showed unsatisfactoryperformance with too low an elastic recovery rate of 50% elongation.

Comparative Example 6

An elastic nonwoven fabric was manufactured from the elastomeric resinB-10 and nonelastomeric resin A-1 as in Example 26, except that theweight ratio of the elastic/nonelastic resin was 30/70, and the spinningrate was 0.17 g per minute per hole for B-1 and 0.40 g per minute perhole for A-1. Properties of the fabric obtained are summarized in Table4. This fabric showed unsatisfactory performance with too low an elasticrecovery rate of 50% elongation.

Comparative Example 7

A melt-blown nonwoven fabric was manufactured from the elastomeric resinB-10 and nonelastomeric resin A-1 in an apparatus comprising twoextruders equipped with a screw 30 mm in diameter, heating elements anda gear pump, side-by-side spinnerets for combined yarns (501 holes 0.3mm in diameter, 500 mm in effective width), an air compressor, an airheater, a collecting conveyor with a polyester net, and a take-up. Theelastomeric and nonelastomeric resins were charged in the respectiveextruders, and melted by heating to 230° C. and 270° C., respectively.The gear pumps were set so that the weight ratio of theelastomeric/nonelastomeric resin was 80/20. The molten resins weredischarged through the spinneret at a rate of 0.12 g per minute perhole. The threads formed were blown onto the conveyor, located at adistance of 25 cm from the spinneret, with the polyester net running ata rate of 1.5 m/min, by means of compressed air at 98 kPa (gauge) heatedto 400° C. The air was removed by a suction unit behind the conveyor.The load on the conveyor was rolled up as elastic nonwoven fabric with abasic weight of 61 g/m². Properties of the fabric are summarized inTable 4. The nonwoven fabric thus obtained, composed of composite fiberyarns, showed unsatisfactory performance with the peeling strengthhigher than the strength under elongation. In fact, the product wasirreversibly elongated when unwound from the roll and was unusable.

Table 1

Table 2

Table 3

Table 4

EFFECT OF THE INVENTION

The elastic nonwoven fabric or laminated elastic nonwoven fabricaccording to the present invention is favorably applicable in disposablediapers, clothes, caps, bandages, tapes and other fiber products thatneed comfortable fit to the body, has adequate elasticity andflexibility, owing to its good elasticity and antiblocking property aswell as adequate strength under elongation. Appropriate selection of theelastomeric and nonelastomeric resins allows manufacture of elasticnonwoven fabric or laminated elastic nonwoven fabric with favorableelasticity and antiblocking property, adequate strength underelongation, and favorable feeling while generating no toxic gases oncombustion and being recyclable.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an example of the arrangement of the spinning holes in aspinneret for manufacture of spunbonded nonwoven fabric according to theinvention. The white circle represents a spinning hole for theelastomeric resin, and the black circle that for the nonelasotmericresin.

TABLE 1 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6Elastomeric resin Resin No. B-1 B-1 B-1 B-1 B-1 B-1 Nonelastomeric resinResin No. A-1 A-1 A-1 A-1 A-1 A-1 Elastomer/nonelastomer weight ratio95/5 90/10 80/20 80/20 70/30 60/40 Manufacture of Manufacturing method*MB MB MB MB MB MB nonwoven fabric Stretching ratio 0 0 0 2.2 0 0Property of Elastomer fiber average diameter μm 12.0 11.5 9.1 9.1 9.09.0 nonwoven fabric Nonelastomer fiber average diameter μm 1.0 1.1 1.21.2 1.2 1.5 Elongation recovery rate of 50% % 100 98 98 98 87 84elongation Strength at 50% elongation N/25 mm 2.1 2.3 2.7 1.0 4.8 6.7Peeling strength N/25 mm 2 2 1 0.8 0.5 0.3 Feeling 80 85 90 95 94 95Basic weight g/m² 60 62 62 60 60 61 Example 7 Example 8 Example 9Example 10 Elastomeric resin Resin No. B-1 B-1 B-1 B-2 Nonelastomericresin Resin No. A-1 A-1 A-1 A-1 Elastomer/nonelastomer weight ratio50/50 85/15 75/25 80/20 Manufacture of Manufacturing method* MB MB MB MBnonwoven fabric Stretching ratio 0 0 0 0 Property of Elastomer fiberaverage diameter μm 9.0 9.3 8.5 2.0 nonwoven fabric Nonelastomer fiberaverage diameter μm 1.7 1.2 1.3 8.0 Elongation recovery rate of 50% % 8298 92 75 elongation Strength at 50% elongation N/25 mm 8.0 2.4 3.4 4.7Peeling strength N/25 mm 0 1 1 3 Feeling 95 89 92 65 Basic weight g/m²60 59 57 62 *MB = Melt blowing SB = Spun-bonding

TABLE 2 Example Example Example Example Example Example 11 12 13 14 1516 Elastomeric resin Resin No B-2 B-1 B-1 B-1 B-1 B-3 Nonelastomericresin Resin No. A-1 A-2 A-2 A-3 A-4 A-1 Elastomer/nonelastomer weightratio 80/20 80/20 80/20 80/20 80/20 80/20 Manufacture of Manufacturingmethod* MB MB MB MB MB MB nonwoven fabric Stretching ratio 2.2 0 2.2 0 00 Property of Elastomer fiber average diameter μm 2.0 9.1 9.1 9.1 9.112.0 nonwoven fabric Nonelastomer fiber average diameter μm 8.0 1.5 1.51.6 1.2 1.3 Elongation recovery rate of 50% % 75 98 98 98 98 90elongation Strength at 50% elongation N/25 mm 1.0 2.9 1.0 2.2 3.5 9.0Peeling strength N/25 mm 0.8 1 0.8 1 1 1 Feeling 70 85 90 88 82 85 Basicweight g/m² 60 62 60 63 64 58 Example Example Example Example 17 18 1920 Elastomeric resin Resin No. B4 B-5 B-6 B-7 Nonelastomeric resin ResinNo. A-1 A-1 A-1 A-1 Elastomer/nonelastomer weight ratio 80/20 80/2080/20 80/20 Manufacture of Manufacturing method* MB MB MB MB nonwovenfabric Stretching ratio 0 0 0 0 Property of Elastomer fiber averagediameter μm 8.0 7.5 8.0 27.0 nonwoven fabric Nonelastomer fiber averagediameter μm 1.3 1.2 1.1 1.4 Elongation recovery rate of 50% % 92 83 8698 elongation Strength at 50% elongation N/25 mm 3.0 3.0 3.1 11.0Peeling strength N/25 mm 1 1 1 1 Feeling 87 84 82 67 Basic weight g/m²60 60 60 62 *MB = Melt blowing SB = Spun-bonding

TABLE 3 Example 21 Example 22 Example 23 Example 24 Example 25Elastomeric resin Resin No B-8 B-9 B-1 B-1 B-1 Nonelastomeric resinResin No. A-1 A-1 A-1 A-1 A-1 Elastomer/nonelastomer weight ratio 80/2080/20 80/20 80/20 80/20 Manufacture of Manufacturing method* MB MB MB MBMB nonwoven fabric Stretching ratio 0 0 0 0 0 Property of Elastomerfiber average diameter μm 8.5 9.0 12.5 9.0 15.0 nonwoven fabricNonelastomer fiber average diameter μm 1.5 1.7 18.0 5.0 5.0 Elongationrecovery rate of 50% % 83 82 90 90 90 elongation Strength at 50%elongation N/25 mm 5.0 5.5 3.5 3.4 4.0 Peeling strength N/25 mm 1 1 2.82.7 2.5 Feeling 75 75 66 68 69 Basic weight g/m² 61 61 60 58 60 Example26 Example 27 Example 28 Example 29 Elastomer resin Resin No. B-1 B-5B-1 B-5 Nonelastomer resin Resin No. A-1 A-1 A-1 A-1Elastomer/nonelastomer weight ratio 80/20 80/20 80/20 80/20 Manufactureof Manufacturing method* SB SB SB SB nonwoven fabric Stretching ratio 00 2.2 2.2 Property of Elastomer fiber average diameter μm 25.0 27.0 25.027.0 nonwoven fabric Nonelasomer fiber average diameter μm 18.0 18.018.0 18.0 Elongation recovery rate of 50% % 90 90 92 92 elongationStrength at 50% elongation N/25 mm 3.0 4.5 1.0 1.0 Peeling strength N/25mm 1 1 0.8 0.8 Feeling 75 75 80 80 Basic weight g/m² 60 60 58 58 *MB =Melt blowing SB = Spun-bonding

TABLE 4 Comparative Comparative Comparative Comparative Example 1Example 2 Example 3 Example 4 Elastomeric resin Resin No. B-1 B-1 B-1B-1 Nonelastomeric resin Resin No. A-1 A-1 no A-1 Elastomer/nonelastomerweight ratio 99/1 90/10Blend 100/0 40/60 Manufacture of Manufacturingmethod* MB MB MB MB nonwoven fabric Stretching ratio 0 0 0 0 Property ofElastomer fiber average diameter μm 16.0 7.0 16.0 7.0 nonwoven fabricNonelastomer fiber average diameter μm 0.2 7.0 — 3.0 Elongation recoveryrate of 50% % 100 97 100 68 elongation Strength at 50% elongation N/25 m2.2 2.2 1.5 8.7 Peeling strength N/25 m 3.5 3.5 4 0 Feeling 65 67 50 80Basic weight g/m² 59 62 61 60 Comparative Comparative ComparativeExample 5 Example 6 Example 7 Elastomer resin Resin No. B-1 B-10 B-10Nonelastomer resin Resin No. A-1 A-1 A-1 Elastomer/nonelastomer weightratio 50/50Blend 30/70 90/10 Manufacture of Manufacturing method* MB SBMB nonwoven fabric Stretching ratio 0 0 0 Property of Elastomer fiberaverage diameter μm 6.5 15.0 10.0 nonwoven fabric Nonelasomer fiberaverage diameter μm 6.5 20.0 Elongation recovery rate of 50% % 65 60 98elongation Strength at 50% elongation N/25 m 8.7 9.0 2.3 Peelingstrength N/25 m 0 0 2.7 Feeling 80 80 80 Basic weight g/m² 62 60 60 *MB= Melt blowing SB = Spun-bonding

1. An elastic nonwoven fabric consisting of one layer wherein a longelastomeric fiber and a long nonelastomeric fiber are uniformly mixedtogether by spinning with a melt-blowing method that uses a spinnerethaving both a spinning hole for discharging elastomeric resin andanother spinning hole for discharging nonelastomeric resin thereon,wherein a ratio of said long elastomeric fiber to said longnonelastomeric fiber ranges from 50/50 to 95/5 on a weight basis, saidlong elastomeric fiber has an average diameter (Bd) of 5 to 40 μm, anelongation recovery rate of the elastic nonwoven fabric after 50%elongation is 70% or higher, a separation resistance of two sheets ofthe same is equal or less than the strength at 50% elongation, and aratio of Bd to an average diameter (Ad) of said long nonelastomericfiber is no less than
 2. 2. An elastic nonwoven fabric according toclaim 1, wherein the said long elastomeric fiber comprises at least oneof the group consisting of elastomeric polystyrenes and elastomericpolyolefins.
 3. An elastic nonwoven fabric according to claim 1, whereinthe said long nonelastomeric fiber has an average diameter (Ad) of 1 to20 μm.
 4. A laminated elastic nonwoven fabric manufactured by laminatingat least one item chosen from the group consisting of a nonwoven fabricdifferent from one according to claim 1, film, web, textile, knit andfiber bundle, to an elastic nonwoven fabric according to claim
 1. 5. Afiber product which employs the elastic nonwoven fabric according toclaim
 1. 6. A fiber product which employs the laminated elastic nonwovenfabric according to claim 4.